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OPTIMIZATION OF MANAGEMENT OF LIQUID RADIOACTIVE WASTE GENERATED IN RESEARCH AND EDUCATION CENTRES

OPTIMIZATION OF MANAGEMENT OF LIQUID RADIOACTIVE WASTE GENERATED IN RESEARCH AND EDUCATION CENTRES. Macías M T 1 , Pérez J 2 , Pulido J 2 , Sastre G 2 , Sánchez A 3 , Usera F 4 1 Instituto de Investigaciones Biomédicas “Alberto Sols” (CSIC-UAM), Spain 2 Universidad de Alcalá de Henares, Spain

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OPTIMIZATION OF MANAGEMENT OF LIQUID RADIOACTIVE WASTE GENERATED IN RESEARCH AND EDUCATION CENTRES

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  1. OPTIMIZATION OF MANAGEMENT OF LIQUID RADIOACTIVE WASTE GENERATED IN RESEARCH AND EDUCATION CENTRES Macías M T1, Pérez J2, Pulido J2, Sastre G2, Sánchez A3, Usera F4 1Instituto de Investigaciones Biomédicas “Alberto Sols” (CSIC-UAM), Spain 2Universidad de Alcalá de Henares, Spain 3Centro de Biología Molecular “Severo Ochoa” (CSIC-UAM), Spain 4Centro Nacional de Biotecnología (CSIC), Spain

  2. INTRODUCTION Improving the management of the radioactive waste generated in radioactive installations One of the most important issues is to reduce the volume of the waste, carrying out adequate clearanceprocedures In Spain, some guideshave been published for management of residual materials, but there are some issues that have not been solved yet

  3. Objectives of the research project: “Procedures to optimize the management of waste materials generated at research and teaching centres” With the aim of trying to solve these issues, four large research and teaching centres have carried out a research project with a grant from ENRESA Objectives: • Radiological and chemical characterizationof radioactive waste • Propose a correct management of • filled scintillation vials • waste generated in electronic microscopic techniques • Aqueous and organic liquid waste This is the most important objective of the project. Here we present the results obtained

  4. MATERIAL AND METHODS Measurement of the Liquid Waste Activity Concentration Scintillation counting was used. Absolute activity and radioactive concentration were determined applying the protocols indicated in the document[1] Calculation of Reference Values of Activity for Organic Liquid Waste • The study focuses on the incineration of C-14 and H-3 waste • Effective dose limit established for individuals should be ≤ 10 μSv/year • Pathways of exposure: inhalation, ingestion and external irradiation • The individual can be exposed for 24 h, 365 days/year • The scenery contemplates the following conditions: • Atmospheric standard conditions. • Gaseous discharge reaches up to 1 m high on a building of 10 m • Wind speed is 1 m/s going towards where an individual lives 25 % of the time • The distance from the gaseous discharge to the individual is 100 m • The theoreticalmodel was made by “Unidad de Protección Radiológica del Público y del Medio Ambiente” (CIEMAT). [1] Macías, M.T., Pulido, J., Ruiz, A., Sánchez, M., Sánchez, A. y Usera, F. 2002.Guía técnica de gestión de materiales residuales con contenido radiactivo en centros de investigación y docencia. Sociedad Española de Protección Radiológica, publicación nº 7. (Senda. Madrid).

  5. MATERIAL AND METHODS (2) Calculation of Reference Values of Activity Concentration for Aqueous Liquid Waste Final disposal: discharge to the normal sewerage system CSN, Regulatory Body in Spain, limits the annual amount of discharge to a maximum of 10 GBq of 3H, 1 GBq of 14C and 1 GBq as the sum of the rest of radionuclides, ensuring that ALIing is not exceeded Taking into account these parameters, we must make the following calculations: • ALIing: annual limits of intake by ingestion (fulfilling the annual effective dose limit of 1 mSv) • Cvmax: maximum limit of activity concentration in the final point of the sewerage system (annual ingestion rate of 600 l) • CvPI: maximum activity concentration of the waste to be discharged in the initial point of the sewerage system (knowing the daily volume of water evacuated from the building) e(g)j: committed effective dose coefficient Vc: liquid waste volume in the container Vec: water volume released in the centre daily

  6. RESULTS Characterization of Liquid Waste Most of the liquids had low activity concentration. They are clear candidates for clearance, some of them may be directly and others should be stored for decay if they do not have long half-lives

  7. RESULTS (2) Reference Clearance Levels Proposed for Organic Liquid Waste To obtain the effective dose of 10 μSv/year with a continual emission is necessary of: The calculation of the reference clearance values has been performed using the indicated data and the volume of liquid waste generated in Spain (495 liters for 2008) The liquid waste with a radioactive concentration that is lower than these values may be incinerated with the Spanish regulatory body approval When both radionuclides are incinerated: a: year If it is necessary to incinerateboth radionuclides simultaneously:

  8. RESULTS (3) Reference Clearance Levels Proposed for Aqueous Liquid Waste Annual limits of intake by ingestion (ALI ing) and maximum limit of activity concentration at the final point of the normal sewerage system (CVmax) obtained for several radionuclides Vc: liquid waste volume in the container Vec: water volume released in the centre daily Maximum limit of activity concentration to be discharged in the initial point of the normal sewerage system (CvPI) for 3H and 14C in a facility that releases 45,000 liters daily OBT: Organically Bound Tritium

  9. CONCLUSIONS • If the incineration is the last part of the organic liquids management, it would reach the clearance levels if the radioactive concentration is lower than 7.8·108 Bq/l of 3H or 1.09·107 Bq/l of 14C, taking into account a general production of 495 liters (Spain, 2008) • The 3H and 14C radioactive concentrations obtained in the characterized techniques are lower than the values indicated, which makes it possible to transfer the liquids to a hazardous waste company for its incineration • As regards the aqueous liquids, the Cvpi have been determined for several radionuclides assuming that a water volume of 45,000 l/day is released. The radioactive concentrations for 3H and 14C obtained in the characterized techniques were lower than the values indicated. Therefore these liquids could be discharged directly into the normal sewerage system • All radioactive installations need to perform their own calculations in order to obtain reference values to make the adequate clearance of their aqueous liquids. We are currently preparing a technical guide based on this study. This guide will contain the most suitable protocols to determine the management for all types of radioactive waste • Nowadays the organic liquid waste management is an unsolved problem. This work emphasizes the necessity to establish reference clearance values for organic liquid waste, suggesting the use of the obtained results to determine the indicated values. These values should be approved by the regulatory body and published in a technical document

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